instmctions): The Imaging and Cell Sorting Core (Core C) is a new Core facility that was added to the Program Project in response to new technological opportunifies and the changing needs of Program investigators. The overall goal of the Core is to facilitate and enhance the research efforts in the individual Units by offering the following imaging and fiow cytometry services to Program members: 1. Advanced microscopic imaging a. Light and confocal microscopy b. Laser capture and microdissection c. Assistance in experimental design and data analysis of imaging studies 2. Multi-parameter flow cytometry and cell sorting a. Cell subset analysis b. Fluorescence-activated cell sorting The Core facilities are located within easy walking distance of the Research Units in the School of Medicine on the UCSD Main Campus in La Jolla. The necessary equipment and support staff is available in the Core facilities, so the Core is fully functional at this time and requires no additional investment in new equipment. RELEVANCE (See instructions): Analysis of cell numbers and location in whole tissues, and the ability to isolate and characterize specific cell types, are critical for the success of molecular physiologic research in immunology. The necessary tools and expertise is only available through shared resource arrangements.